The Glyph Transformer is on the Tools menu (unless you are using the Home Edition of FontCreator). Click the folder icon to open the Eastern Europe script.

Transform Wizard.png (12.09 KiB) Viewed 432 times

If you're using the Home Edition you can select the glyphs from the Insert Character dialogue.

Insert Characters.png (27.44 KiB) Viewed 432 times

After adding the characters that you need, select the base glyph and the accent in the Glyph Overview, copy them and paste them into the relevant new (empty) glyph.

Glyph Overview.png (101.99 KiB) Viewed 432 times

Then align them and set the side bearing to match the base glyph. Right-click on the base glyph, and open it in a new window to see the side-bearings, then close the new window, and apply the correct side-bearing from the glyph properties toolbar.

Select each of the "Insert Characters" commands in the Transform Wizard dialogue, and then click on the Validate button. It will tell you how many new characters will be added. However, if they already exist, none will be added.